Surgical retraction mechanism

ABSTRACT

A retraction mechanism has been developed for use with a hand held surgical apparatus. The retraction mechanism includes a motor, a first speed reducing mechanism, a clutch mechanism incorporating a second speed reducing mechanism, and a shaft. The first speed reducing mechanism is configured to be driven by a motor. The second speed reducing mechanism has a locked state and an unlocked state. In addition, the clutch mechanism is disposed in mechanical cooperation with the first speed reducing mechanism. The shaft is configured to rotate upon activation of the motor the second speed reducing mechanism is in the locked state. The rotation of the shaft retracts a firing drive of the hand held surgical apparatus.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of and priority to U.S.Provisional Application Ser. No. 61/081,456 filed on Jul. 17, 2008, theentire contents of which are incorporated herein by reference

BACKGROUND

1. Technical Field

The present disclosure relates to hand held surgical stapling apparatus.More particularly, the present disclosure relates to retractionmechanism for hand held surgical stapling apparatus.

2. Background of Related Art

Some surgical apparatus are capable of fastening tissue layers. Ingeneral, surgical fastening apparatus include two elongated jaw membersdesigned for capturing or clamping tissue. One jaw member typicallycontains a staple cartridge. The staple cartridge houses a plurality ofstaples. Typically, the staple cartridges include at least two lateralrows of retention slots. Each retention slot is adapted to receive astaple. The other jaw member has an anvil that defines a surface forforming the staple legs as the staples are driven from the staplecartridge. The stapling operation is usually effected by cam membersthat translate through the staple cartridge. These cam members areconnected to a firing drive that moves from a proximal position to adistal position when a user actuates the surgical stapling apparatus.Upon actuation of the surgical stapling apparatus, the firing drivemoves in a distal direction and causes the cam members to move from aproximal position to a distal position through the staple cartridge.While the cam members translate through the staple cartridge, these cammembers sequentially act on staple pushers positioned along the staplecartridge to eject the staples from the staple cartridge. The surgicalstapling apparatus may further include a knife operatively attached tothe cam members and positioned between two rows of staple slots.Alternatively, the knife may be attached to the drive member rather thanthe cam member. Since the knife is operatively attached to the cammembers, the knife moves from proximal position to a distal position,while the cam members translate from a proximal portion to a distalportion of the staple cartridge. As the knife moves through the staplecartridge, it cuts or opens tissue positioned between the jaw members.

Another surgical stapling apparatus applies a double row of staples oneach side of the incision. This surgical stapling apparatus has adisposable loading unit wherein a cam member moves from a proximalposition to a distal position through an elongate guide path between twosets of staggered staple carrying grooves. Staple drive members arelocated within the grooves and are positioned in such a manner so as tobe contacted by the longitudinally moving cam member. The staple memberseject the staples in the staple cartridge as the cam member movesaxially along the elongate guide path.

Each of the apparatus described hereinabove is designed for use inconventional surgical procedures wherein surgeons have direct manualaccess to the operative site. In endoscopic or laparoscopic procedures,however, surgery is performed through a small incision or through anarrow cannula inserted through small entrance wounds in the skin.Endoscopic surgical stapling devices have been developed to address thespecific needs of endoscopic and laparoscopic surgical procedures. A fewexamples of endoscopic surgical stapling devices are disclosed in U.S.Pat. No. 5,307,976; U.S. Pat. No. 5,312,023; U.S. Pat. No. 5,326,013;U.S. Pat. No. 5,332,142; and U.S. Pat. No. 6,241,139, the entirecontents of each of which are incorporated herein by reference.

As discussed above, the cam members of the surgical stapling apparatusdiscussed above are operatively connected to a firing drive.Consequently, a distal motion of the firing drive causes the cam membersto move in a distal direction. The surgical stapling apparatus devicesdiscussed above may further include a retraction mechanism to return thefiring drive to a proximal position. Given that the cam members arecoupled to the firing drive, the retraction mechanism also moves the cammembers (along with the firing drive) to a proximal position. Theretraction mechanism includes a pair of retractor knobs movablypositioned along a barrel portion of a handle assembly. The retractionknobs are manually pulled proximally to return the firing drive to itsproximal position after firing the surgical stapling apparatus.

Other endoscopic stapling apparatus include powered retractionmechanisms. For instance, U.S. patent application Ser. No. 11/784,804,filed Apr. 9, 2007, the entire contents of which is hereby incorporatedby reference, discloses a surgical stapling apparatus including apowered retraction mechanism. An embodiment of this retraction mechanismincludes a motor operatively associated with a pulley and a slip clutch.The pulley is configured to retract the firing drive of the surgicalstapling apparatus once the slip clutch moves to its engaged position.

The surgical apparatus described above have provided significantclinical benefits. Nonetheless, improvements to these instruments arepossible. For instance, it would be beneficial to provide a more compactretraction mechanism for surgical apparatus.

SUMMARY

The present disclosure relates to a retraction mechanism for use with ahand held surgical apparatus. An embodiment of the presently disclosedretraction mechanism includes a motor, a first speed reducing mechanism,a clutch mechanism incorporating a second speed reducing mechanism, anda shaft. The first speed reducing mechanism is adapted to be driven bythe motor. The second speed reducing mechanism has a locked state and anunlocked state. The clutch mechanism is disposed in mechanicalcooperation with the first speed reducing mechanism. The shaft isconfigured to rotate upon activation of the motor when the second speedreducing mechanism is in the locked state. In operation, a rotation ofthe shaft retracts a firing drive of a surgical apparatus. In oneembodiment, the second speed reducing mechanism is a planetary clutch.

In an alternative embodiment, the retraction mechanism includes a motor,a speed reducing mechanism, a planetary clutch, and a firing drive. Themotor is disposed in electromechanical cooperation with a speed reducingmechanism. The planetary clutch has a locked state and an unlockedstate. Additionally, the planetary clutch is operatively coupled to thespeed reducing mechanism. The firing drive is adapted to actuate asurgical tool. Moreover, the firing drive is adapted to move proximallyin response to a rotation of a shaft driven by the planetary clutchwhile in the locked state. The shaft rotates upon activation of themotor.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical apparatuses andretraction mechanism are described herein with reference to thedrawings:

FIG. 1 is a perspective view of a surgical apparatus according to anembodiment of the present disclosure;

FIG. 2 is a top view of the surgical apparatus of FIG. 1;

FIG. 3 is a side elevational view of the surgical apparatus of FIG. 1;

FIG. 4 perspective cross-sectional view of a handle assembly of asurgical apparatus according to an embodiment of the present disclosure;

FIG. 4A is a perspective view of a firing drive of the handle assemblyof FIG. 4

FIG. 4B is a perspective view of the firing drive of the handle assemblyof FIG. 4;

FIG. 4C is perspective view of a connector of the handle assembly ofFIG. 4;

FIG. 5 is side cross-sectional view of the handle assembly of FIG. 4;

FIG. 6 is a perspective view of a retraction mechanism operativelyassociated with a lever in accordance with an embodiment of the presentdisclosure;

FIG. 7 is a side elevational view of the retraction mechanism and leverof FIG. 6;

FIG. 8 is a perspective view of the retraction mechanism of FIG. 6;

FIG. 9 is a side elevational view of the retraction mechanism of FIG. 6;

FIG. 10 is a perspective view of a portion of the retraction mechanismof FIG. 6; and

FIG. 11 is front elevational view of a portion of the retractionmechanism of FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

Embodiments of the presently disclosed surgical apparatus and retractionmechanism for use therewith will now be described in detail withreference to the drawings in which like reference numerals designateidentical or similar elements in each of the several views. In thedescription and in the claims, the term “proximal,” as is traditional,will refer to the end of the apparatus, or a portion thereof, that isclosest to the operator, while the term “distal,” will refer to the endof the apparatus, or a portion thereof, that is farthest from theoperator. In addition, the singular forms, such as “a,” “an,” and “the,”include the plural form. Likewise, all plural forms include the singularform, unless clearly stated otherwise.

With reference to FIGS. 1-3, an embodiment of the presently disclosedsurgical apparatus is generally designated as 10. In the interest ofbrevity, this disclosure will focus primarily on systems, methods andstructures for returning a firing drive of surgical apparatus 10 to itsretracted or proximal position. U.S. Pat. No. 6,953,139, the entiredisclosure of which is incorporated herein by reference, contains adetailed discussion of the remaining components and methods of use ofsurgical apparatus 10.

Surgical apparatus 10 is an endoscopic or laparoscopic instrumentincluding a handle assembly 12 and an elongated body 14 extendingtherefrom. A single use loading unit (“SULU”) 16 is releasably securedto a distal end of elongated body 14. Although the drawings show SULU16, one skilled in the art will recognize that any other suitable toolor end effector can be releasably secured to elongated body 14. Inparticular, SULU 16 includes an elongate portion 31 disposed inmechanical cooperation with elongate body 14. Specifically, a proximalend 31 a of the elongate portion 31 is operatively connected to elongatebody 14. In turn, a distal end 31 b of elongate portion 31 is coupled toa tool assembly 17 of SULU 16.

Tool assembly 17 includes a cartridge assembly 18 adapted to retain aplurality of surgical staples in retention slots 18 a. Retention slots18 a are arranged in rows that extend along a tissue contacting surface18 b. These rows of retention slots 18 a correspond to rows of staples.While retention slots 18 a may be arranged in numerous ways, anembodiment of the present disclosure includes retention slots 18 apositioned on both sides of a knife channel 18 c disposed on tissuecontacting surface 18 b. Knife channel 18 c extends longitudinally alongtissue contacting surface 18 b and is adapted to receive a knifetherealong. In operation, a knife slides through knife channel 18 cduring or after stapling.

Aside from cartridge assembly 18, tool assembly 17 has an anvil assembly20. Anvil assembly 20 includes a tissue contacting surface 20 a adaptedto deform staples during the stapling process. In addition, anvilassembly 20 includes a pivot pin 21. Pivot pin 21 or any other suitablefastening device, such as a hinge, pivotably connects anvil assembly 20and cartridge assembly 18 at their respective proximal ends. The pivotpin 21 facilitates movement of anvil assembly 20 between an openposition spaced from cartridge assembly 18 and an approximated orclamped position in juxtaposed alignment with cartridge assembly 18. Therelative motion of anvil assembly 20 with respect to cartridge assembly18 allows the actuation of SULU 16 to clamp and immobilize tissue.

Altogether, SULU 16 is configured to apply at least one row of staples.SULUs 16 may have various staple line lengths and configurations. Insome embodiments, SULUs 16 have staple line lengths measuring from about30 mm to 60 mm in length. In addition to staple line length, otherfeatures of SULU 16 can adjust to the different needs depending on thecircumstances.

For example, SULU 16 may include a tool assembly 17 pivotable about itsproximal end, as disclosed in U.S. Pat. No. 6,953,139, the disclosure ofwhich is hereby incorporated by reference. In this embodiment, a usercontrols the pivotable movement of tool assembly 17 through anarticulation lever 30 positioned on handle assembly 12. Articulationlever 30 is pivotably engaged to a cam member (not shown) positionedinside handle assembly 12. The cam member, in turn, is operativelycoupled to a translation member (not shown). The translation member ispositioned within handle assembly 12, and the engagement between the cammember and the translation member inhibits rotation of the translationmember, but allows linear movement of the translation member in responseto a pivotal movement of articulation lever 30. A distal end of thetranslation member is coupled to a proximal end of a first articulationlink (not shown). During operation, a linear motion of the translationmember causes a corresponding linear movement of the first articulationlink. The first articulation link, which is mainly located within handleassembly 12, is operatively connected to a second articulation link (notshown). The second articulation link is configured to move linearly inresponse to a linear movement of the first articulation link and isengaged to a laterally offset inner portion of a mounting assembly 23.Mounting assembly 23 includes a pivot pin 25 and pivotably interconnectstool assembly 17 and elongate portion 31. Since the second articulationlink is laterally offset from pivot pin 25, a linear movement of thesecond articulation links causes mounting assembly 23 to pivot aboutpivot pin 25 to articulate tool assembly 17.

In addition to controlling the pivoting motion of tool assembly 17,handle assembly 12 directs the actuation of tool assembly 17. To thisend, handle assembly 12 includes a stationary handle member 22, amovable handle member 24, and a barrel portion 26 defining alongitudinal axis “X.” Barrel portion 26 has a rotatable member 28mounted on a distal portion thereof. In use, rotatable member 28facilitates rotation of elongated body 14 with respect to handleassembly 12.

With reference to FIGS. 4, 4A-4C, and 5, barrel portion 26 encloses afiring drive 2 including a toothed rack 38 and a driving pawl 44.Driving pawl 44 includes a mounting portion 44 a and an engagementportion 44 b adapted to engage toothed rack 38. A pivot pin 51 pivotablyinterconnects one end of movable handle member 24 (FIG. 1) and drivingpawl 44 and allows engagement portion 44 a of driving pawl 44 to pivottoward toothed rack 38 in response to a movement of movable handlemember 24 toward stationary handle member 22. Consequently, driving pawl44 is mounted to selectively engage toothed rack 38 and advance firingdrive 2 in a distal direction in response to manipulation of movablehandle member 24 (see FIG. 1) through an actuating stroke. A biasingmember 47, which may be a torsion spring, is positioned to urge anengagement portion 44 b of driving pawl 44 toward toothed rack 38. Themounting portion 44 a of pawl 44 is adapted to interact with an abutmentwall 45 mounted within barrel portion 26. As discussed above, movablehandle member 24 is pivotably connected to pawl 44 so that it is capableof moving engagement portion 44 b of driving pawl 44 into contact withtoothed rack 38 to advance the firing drive 2 linearly in the distaldirection. As a consequence, driving pawl 44 is rotated in and out ofengagement with the toothed rack 38 of firing drive 2 upon manipulationof movable handle member 24. Firing drive 2 is operatively connected toa control rod (not shown). The control rod, which is adapted to movelinearly in response to a linear motion of firing drive 2, isoperatively coupled to a cam roller (not shown) disposed in mechanicalcooperation with a anvil assembly 20. The cam rollers are configured tomove in a distal direction along a portion of anvil assembly 20 when thecontrol rod is moved distally. When the cam rollers move in distaldirection along anvil assembly 20, anvil assembly 20 pivots about pivotpin 21 toward cartridge assembly 18 (See FIGS. 1-3). The control rod isalso operatively connected to a cam member (not shown) configured tourge the staples out of the cartridge assembly 18. In operation, the cammembers move from a proximal position to a distal position in responseto a distal motion of the control rod. As the cam members move distally,the cam members act on staple pushers (not shown) and eject the staplesresting on those staple pushers. While ejecting from cartridge assembly18, the staples exit from cartridge assembly 18 through retention slots18 a and move toward the anvil assembly 20 to staple tissue.

In operation, a user fires surgical apparatus 10 by pivoting movablehandle member 24 toward stationary handle 22 against the bias of torsionspring 47 to move driving pawl 44 into engagement with toothed rack 38on firing drive 2. Consequently, the pivotal motion of movable handlemember 24 causes driving pawl 44 to engage toothed rack 28 and drivesfiring drive 2 distally. The distal advancement of firing drive 2 causesthe control rod to move distally. When the control rod moves distally,the cam members move along anvil assembly 20 and urge anvil assembly 20toward cartridge assembly 18 to clamp tissue positioned between anvilassembly 20 and cartridge assembly 18. The distal movement of thecontrol rod also causes the cam members to move in distal direction.When the cam members move distally, the cam members move the staplepushers toward the anvil assembly 20. Since the staples seat on thestaple pushers, the staples are ejected from the cartridge assembly 18when the staple pushers move toward anvil assembly 20.

In one embodiment, to complete the staple firing operation, movablehandle member 24 is once again approximated toward stationary handle 22,causing driving pawl 44 to engage toothed rack 38 and advance firingdrive 2 in a distal direction another 15 mm. Thus, in this embodiment,two complete strokes of actuation handle 24 advance firing drive 2thirty (30) mm within barrel portion 26, causing the sequential ejectionof all the surgical staples in cartridge assembly 18. If desired, theoperator can incrementally advance firing drive 2 by multiple shortstrokes, wherein the minimum advancement is dictated by the lineardistance between the teeth on rack 38. Therefore, while two completestrokes of a stroke distance of 15 mm may be used to fire a 30 mmdisposable loading unit, complete strokes are not necessary or required.Surgical apparatus 10 may be configured to have various strokedistances.

A pair of retractor knobs 32 is connected to a proximal end of firingdrive 2. A coupling pin 48 interconnects both retraction knobs 32 andfacilitates translation of retractor knobs 32 along barrel portion 26.Specifically, at least a portion of coupling pin 48 is dimensioned andconfigured to translate within a pair of longitudinal slots 34 a formedalong barrel portion 26, as seen in FIG. 1. A release plate 64 isoperatively associated with firing drive 2 and is mounted for movementwith respect thereto in response to manipulation of retractor knobs 32.A pair of spaced apart pins 29 extends outwardly from a lateral face offiring drive 2 to engage a pair of corresponding angled cam slots 40formed in release plate 64, as shown in FIG. 4A. U.S. Pat. No.7,044,353, the disclosure of which is hereby incorporated by referenceherein, describes in detail the structure and manual operation of thefiring drive 2 and release plate 64. In brief, a user manuallytranslates retractor knobs 32 in a proximal direction to retract firingdrive 2 to its proximal position. As firing drive 2 moves proximally,the cam members operatively associated with to firing drive 2 also moveproximally.

To enable retraction, firing drive 2 includes a distally biasedconnector 42 having distal and proximal ends 42 a, 42 b. Connector 42 ismounted on a top portion of firing drive 2 and has a hole 42 cdimensioned and configured for receiving coupling pin 48. A flexiblemember 19 interconnects connector 42 and a retraction pulley 9. Thepresent disclosure envisions that flexible member 19 can be a cable, achain, or any other suitable device capable of interconnecting connector42 and retraction pulley 9. In particular, a first end 19 a of flexiblemember 19 is attached to the proximal end 42 b of connector 42. A secondend 19 b of flexible member 19 is attached to retraction pulley 9, asseen in FIG. 11.

Referring to FIGS. 5-9, retraction mechanism 3 is generally positionedin parallel with longitudinal axis “X” within handle assembly 12 andfacilitates retraction of firing drive 2 to a proximal position. To thisend, retraction mechanism 3 is operatively associated with firing drive2 through flexible member 19. In addition, retraction mechanism 3includes a motor 6, and optionally a gearbox 6 a, disposed inelectro-mechanical cooperation with a speed reducing mechanism ortransmission 8. Particularly, a transmission shaft 46 is mounted tomotor 6. A coupling 7 interconnects transmission shaft 46 and speedreducing mechanism 8. Speed reducing mechanism 8 effectively reduces therotational motion supplied by motor 6. In one embodiment, speed reducingmechanism 8 is a worm gear set that includes a first gear 8 a configuredto mesh with a second gear 8 b. First gear 8 a is secured to coupling 7and, in operation, rotates in response to a rotation of transmissionshaft 46. In turn, the rotation of first gear 8 a causes the rotation ofsecond gear 8 b.

Referring to FIGS. 8-11, second gear 8 b is rotatably connected to ahollow shaft 78. Hollow shaft 78 is adapted to rotate upon rotation ofsecond gear 8 b. Further, hollow shaft 78 has a bore 76 extendingtherethrough. Bore 76 is adapted to receive at least a portion of ashaft 13. Hollow shaft 78 operatively connects second gear 8 b and aclutch mechanism 11. Therefore, clutch mechanism 11 is disposed inrotational cooperation with speed reducing mechanism 8. In the depictedembodiment, clutch mechanism 11 is a planetary clutch. The presentdisclosure, however, envisions that clutch mechanism 11 may be any othersuitable clutch. Clutch mechanism 11 has a locked and an unlocked state.A strap 62 and a spring loaded lever 5 (FIGS. 6 and 7) are designed towork together to switch clutch mechanism 11 from a locked state to anunlocked state and vice versa.

In particular, strap 62 is adapted to engage and lock clutch mechanism11 upon actuation of lever 5, as shown in FIG. 6. In one embodiment,lever 5 includes a trigger 5 a, an elongated section 5 b, and a hole 5c. Hole 5 c is configured to receive a pivot pin 52. Pivot pin 52, orany suitable device, pivotably connects lever 5 with retractionmechanism 3. Lever 5 rotates about pivot pin 52 upon manual manipulationby a user. Lever 5 further includes an opening 5 d adapted to receive atleast a portion of strap 62. A portion of strap 62 surrounds a ring gear77 and another portion of strap 62 is operatively connected to lever 5.In one embodiment, a portion of strap 62 is directly connected to theframe of retraction mechanism 3. During operation, a distal translationof trigger 5 a of lever 5 moves a portion of strap 62 distally to lockclutch mechanism 11. As lever 5 moves distally, the force exerted bystrap 62 along the circumference of ring gear 77 increases and inhibitsrotation of ring gear 77. To unlock ring gear 77, a user may returnlever 5 to its initial position. Alternatively, lever 5 may return toits initial position under the influence of a biasing device such as acoil spring.

With reference to FIGS. 8-11, clutch mechanism 11 may be composed of aplanetary gear system. Clutch mechanism 11 includes a plurality ofplanet gears 86, a center ring 15, a sun gear 84 and ring gear 77. Sungear 84 includes teeth 84 a and a lumen 54 extending therethrough. Lumen54 is adapted to receive shaft 13. A portion of shaft 13 is disposedwithin hollow shaft 78. During operation, hollow shaft 78 rotates aroundat least a portion of shaft 13. Hollow shaft 78 is disposed inmechanical cooperation with planet gears 86 and, as previouslydiscussed, gear 8 b.

Planet gears 86 are positioned around sun gear 84. Therefore, eachplanet gear 86 is configured to rotate about its center and about thecenter of sun gear 84. In addition, each planet gear 86 includes aplurality of teeth 86 a and a bore 86 b. Teeth 86 a are configured tomesh with teeth 84 a of sun gear 84. Each bore 86 b is configured toreceive a shaft 60. Shaft 60 connects each planet gear 86 with centerring 15.

Center ring 15 interconnects all planet gears 86 and includes twoannular plates 56, 58 disposed in mechanical cooperation with planetgears 16, as shown in FIGS. 10 and 11. Annular plates 56, 58 are eachoperatively attached to opposing sides of planet gears 86. Inparticular, annular plate 58 is also operatively coupled to hollow shaft78. Each annular plate 56, 58 includes a bore 57 adapted to receiveshaft 60.

During use, the actuation of lever 5 presses strap 62 around ring gear77 and immobilizes ring gear 77, thereby placing clutch mechanism 11 inthe locked position. The center of ring gear 77 coincides with thecenter of sun gear 84.

As discussed hereinabove, lumen 54 of sun gear 84 is configured toreceive a shaft 13. Shaft 13 is operatively associated with sun gear 84,retraction pulley 9, and spring motor 80. The spring motor 80, FIG. 8,includes a first spool 64, a second spool 66, and a spring 68interconnecting first and second spools 64, 66. In use, spring motor 80maintains the tension of flexible member 19 and prevents itsentanglement.

Flexible member 19 is operatively secured to retraction pulley 9 as seenin FIG. 11. Retraction pulley 9 has a recess 70 along its circumference.Recess 70 is adapted to receive flexible member 19. Moreover, retractionpulley 9 includes opposing flanges 72, 74. Flanges 72, 74 secureflexible member 19 within recess 70. Flexible member 19 interconnectsthe retraction pulley 9 and the firing drive 2. Particularly, the secondend 19 b of flexible member 19 is attached to retraction pulley 9 ofretraction mechanism 2, and the first end 19 a of flexible member 19 isattached to the proximal end 42 b of connector 42.

Retraction mechanism 3 facilitates retraction of the firing drive 2 of asurgical apparatus 10 after firing. In operation, a physician firessurgical apparatus 10 by manually actuating handle assembly 12. Theoperator may actuate handle assembly 12 with only one hand.Specifically, the user operator manually approximates movable handlemember 24 toward stationary handle member 22 to move firing drive 2distally. The distal translation of firing drive 2 causes anvil assembly20 to move to the approximated position. In addition, the distalmovement of firing drive 2 causes the ejection of the surgical staplesdisposed in retention slots 18 a of cartridge assembly 18. During thisprocess, firing drive 2 translates from a proximal position to a distalposition. Since the flexible member 19 is operatively connected tofiring drive 2, the distal movement of firing drive 2 also causes thedistal translation of flexible member 19. As flexible member 19 movesdistally, it unwinds from retraction pulley 9. At this moment, motor 6is off, clutch 11 is unlocked, and the center ring 15 remains stationaryand serves as a ground for the planet gears 86.

Once the surgical apparatus 10 has been fired, the surgeon has toretract drive 2 to its proximal position to reuse it. If manualretraction is desired, the surgeon may move the firing drive 2 to itsproximal position through manual manipulation of knobs 32. Inparticular, the operator may proximally translate knobs 32 with one handwhile holding the handle assembly 12 with the other hand. The proximaltranslation of knobs 32 causes the proximal movement of firing drive 2.Thereafter, surgical apparatus 10 is once again ready for firing.

If powered retraction is desired, an operator may return firing drive 2to its proximal position by using retraction mechanism 3. The surgeonactivates retraction mechanism 3 through lever 5. Particular, thesurgeon depresses trigger 5 a of lever 5 to activate motor 6 and moveclutch mechanism 11 to its locked position. At this instance, strap 62tightens around ring gear 77 and significantly increases the frictiontherebetween. Consequently, ring gear 77 is fixed to ground.

The motor 6 drives transmission shaft 46. The rotation of transmissionshaft 46 rotates first gear 8 a of speed reduction mechanism 8. Firstgear 8 a meshes with second gear 8 b. The rotary motion of first gear 8a causes the rotation of second gear 8 b. As second gear 8 b rotates,hollow shaft 78 rotates and, in turn, causes the corresponding rotationof center ring 15. Consequently, planet gears 86 revolve inside ringgear 77 and around sun gear 84. Planet gears 86 rotate about theircenter and about the center of sun gear 14. The overall movement ofplanet gears 86 drives sun gear 84. While sun gear 14 rotates, shaft 13rotates pulley 9. Pulley 9 rotates in a counterclockwise direction andwinds flexible member 19 around it. The rotary motion of pulley 9 alsotranslates flexible member 19 in a proximal direction. The proximaltranslation of flexible member 19 moves firing drive 2 to its proximalposition. Once the process described above is complete, the surgicalapparatus is ready for reuse.

During the retraction process, the surgeon may sense that the resistanceto retraction is too large for the motor 6 working alone. If thisoccurs, the surgeon may manually override the retraction mechanism 3.The operator has the option of turning off motor 6 by disengaging lever5. Then, firing drive 2 of surgical apparatus 10 can be manuallyreturned to its proximal position through knobs 32. The method of usingknobs 32 to return firing drive 2 to its proximal position was discussedabove.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications of theembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto. For instance,surgical apparatus 10 may include sensors to monitor the resistance toretraction by the retraction mechanism 3 to actuate warnings or feedbackcontrol of motor 6. Sensors can also be employed to turn motor 6 offwhen firing drive 2 reaches its proximal position.

1. A retraction mechanism for use with a hand held surgical staplingapparatus, comprising: a first speed reducing mechanism adapted to bedriven by a motor; a clutch mechanism incorporating a second speedreducing mechanism having a locked state and an unlocked state, whereinthe clutch mechanism is disposed in mechanical cooperation with thefirst speed reducing mechanism; and a shaft configured to rotate uponactivation of the motor when the second speed reducing mechanism is inthe locked state, wherein a rotation of the shaft retracts a firingdrive of a surgical apparatus.
 2. The retraction mechanism of claim 1,wherein the second speed reducing mechanism is a planetary clutch. 3.The retraction mechanism of claim 1, further comprising a pulley coupledto the shaft, the pulley being operatively connected to the firingdrive.
 4. The retraction mechanism of claim 3, further comprising aflexible member interconnecting the pulley and the firing drive.
 5. Theretraction mechanism of claim 4, further comprising a spring motoradapted to rotationally bias the pulley.
 6. The retraction mechanism ofclaim 5, wherein the spring motor includes a first spool, a secondspool, and a spring interconnecting first and second spools.
 7. Theretraction mechanism of claim 2, further comprising a hollow shaftinterconnecting the first speed reducing mechanism and the planetaryclutch.
 8. The retraction mechanism of claim 7, wherein the hollow shafthas a bore extending therethrough, the bore being adapted to receive atleast a portion of the shaft.
 9. The retraction mechanism of claim 1,wherein the first speed reducing mechanism includes a first gearconfigured to mesh with a second gear.
 10. A retraction mechanism foruse with a surgical apparatus, comprising: a motor disposed inelectromechanical cooperation with a speed reducing mechanism; aplanetary clutch operatively coupled to the speed reducing mechanism,the planetary clutch having a locked state and an unlocked state; and afiring drive adapted to actuate a surgical tool, the firing drive beingadapted to move proximally in response to a rotation of a shaft drivenby the planetary clutch while in the locked state, wherein the shaftrotates upon activation of the motor. H-US-01046 (203-5655)
 11. Theretraction mechanism of claim 10, further comprising a pulley coupled tothe shaft, the pulley being operatively connected to the firing drive.12. The retraction mechanism of claim 11, further comprising a flexiblemember interconnecting the pulley and the firing drive.
 13. Theretraction mechanism of claim 12, further comprising a spring motoradapted to prevent entanglement of the flexible member, the spring motorbeing operatively secured to the pulley.
 14. The retraction mechanism ofclaim 13, wherein the spring motor includes a first spool, a secondspool, and a spring interconnecting first and second spools.
 15. Theretraction mechanism of claim 12, further comprising a hollow shaftinterconnecting the speed reducing mechanism and the planetary clutch.16. The retraction mechanism of claim 15, wherein the hollow shaft has abore extending therethrough, the bore being adapted to receive at leasta portion of the shaft.
 17. The retraction mechanism of claim 10,wherein the speed reducing mechanism includes a first gear configured tomesh with a second gear.